gland

gland

[gland]

an aggregation of cells specialized to secrete or excrete materials not related to their ordinary metabolic needs. Glands are divided into two main groups, endocrine and exocrine. adj., adj glan´dular.

The endocrine glands, or ductless glands, discharge their secretions (hormones) directly into the blood; they include the adrenal, pituitary, thyroid, and parathyroid glands, the islands of Langerhans in the pancreas, the gonads, the thymus, and the pineal body. The exocrine glands discharge through ducts opening on an external or internal surface of the body; they include the salivary, sebaceous, and sweat glands, the liver, the gastric glands, the pancreas, the intestinal, mammary, and lacrimal glands, and the prostate. The lymph nodes are sometimes called lymph glands but are not glands in the usual sense.

Classification of glands according to mode of secretion. From Applegate, 2000.

acinous gland one made up of one or more acini (oval or spherical sacs).

apocrine gland one whose discharged secretion contains part of the secreting cells.

areolar g'sMontgomery's glands.

axillary g's lymph nodes in the axilla.

Bartholin g's two small mucus-secreting glands, one on each side in the lower pole of the labium majus and connected to the surface by a duct lined with transitional cells, which opens just external to the hymenal ring. Their exact function is not clear but they are believed to secrete mucus to moisten the vestibule during sexual excitement. Called also major vestibular glands.

bronchial g's seromucous glands in the mucosa and submucosa of the bronchial walls.

Brunner's g's glands in the submucosa of the duodenum that secrete intestinal juice; called also duodenal glands.

buccal g's seromucous glands on the inner surface of the cheeks; called also genal glands.

bulbocavernous g's (bulbourethral g's) two glands embedded in the substance of the sphincter of the male urethra, posterior to the membranous part of the urethra; their secretion lubricates the urethra; called also Cowper's glands.

cardiac g's mucus-secreting glands of the cardiac part (cardia) of the stomach.

celiac g's lymph nodes anterior to the abdominal aorta.

ceruminous g's cerumin-secreting glands in the skin of the external auditory canal.

cervical g's

1. the lymph nodes of the neck.

2. compound clefts in the wall of the uterine cervix.

ciliary g's sweat glands that have become arrested in their development, situated at the edges of the eyelids; called also Moll's glands.

circumanal g's specialized sweat and sebaceous glands around the anus; called also Gay's glands.

Cobelli's g's mucous glands in the esophageal mucosa just above the cardia.

intestinal g's straight tubular glands in the mucous membrane of the intestines, in the small intestine opening between the bases of the villi, and containing argentaffin cells. Called also crypts or glands of Lieberkühn.

jugular gland a lymph node behind the clavicular insertion of the sternocleidomastoid muscle.

ductless gland one without a duct, of internal secretion; see endocrine g's.

duodenal glands glands in the submucosa of the duodenum, opening into the glands of the small intestine.

Ebner's glands serous glands at the back of the tongue near the taste buds.

eccrine gland , eccrine sweat gland one of the ordinary, or simple, sweat glands, which is of the merocrine type.

endocrine glands organs whose secretions (hormones) are released directly into the circulatory system; they include the pituitary, thyroid, parathyroid, and adrenal glands, the pineal body, and the gonads.

exocrine gland one whose secretion is discharged through a duct opening on an internal or external surface of the body.

fundic glands , fundus glands tubular glands in the mucosa of the fundus and body of the stomach, containing acid- and pepsin-secreting cells.

parathyroid glands small bodies in the region of the thyroid gland, developed from the endoderm of the branchial clefts, occurring in a variable number of pairs, commonly two; they secrete parathyroid hormone and are concerned chiefly with the metabolism of calcium and phosphorus.

pituitary glandhypophysis; the epithelial body of dual origin at the base of the brain in the sella turcica, attached by a stalk to the hypothalamus. It consists of two main lobes, the anterior lobe or adenohypophysis, secreting most of the hormones, and the posterior lobe or neurohypophysis, which stores and releases neurohormones received from the hypothalamus.

preputial glands small sebaceous glands of the corona of the penis and the inner surface of the prepuce, which secrete smegma.

pyloric glands the mucin-secreting glands of the pyloric part of the stomach.

racemose glands glands composed of acini arranged like grapes on a stem.

saccular gland one consisting of a sac or sacs, lined with glandular epithelium.

salivary glands glands of the oral cavity whose combined secretion constitutes the saliva, including the parotid, sublingual, and submandibular glands and numerous small glands in the tongue, lips, cheeks, and palate.

Suzanne's gland a mucous gland of the mouth, beneath the alveolingual groove.

sweat gland a gland that secretes sweat, found in the dermis or subcutaneous tissue, opening by a duct on the body surface. The ordinary or eccrine sweat glands are distributed over most of the body surface, and promote cooling by evaporation of the secretion; the apocrine sweat glands empty into the upper portion of a hair follicle instead of directly onto the skin, and are found only in certain body areas, as around the anus and in the axilla.

thyroid gland an endocrine gland consisting of two lobes, one on each side of the trachea, joined by a narrow isthmus, producing hormones (thyroxine and triiodothyronine), which require iodine for their elaboration and which are concerned in regulating metabolic rate; it also secretes calcitonin.

gland

a. Any of various organs or cell groups, such as the adrenal glands and the salivary glands, that are of endothelial origin and secrete a substance that is used or excreted by the body.

b. Any of various organs, such as lymph nodes, that resemble true glands but perform a nonsecretory function.

2. Botany An organ or a structure that secretes a substance.

gland

Etymology: L, glans, acorn

any one of many organs in the body comprising specialized cells that secrete or excrete materials not related to their ordinary metabolism. Some glands lubricate; others, such as the pituitary gland, produce hormones; hematopoietic glands, such as the spleen and certain lymph nodes, take part in the production of blood components. Exocrine glands discharge their secretions into ducts. They may be classified by the shape and complexity of their duct systems. Endocrine glands are ductless and discharge their secretions directly into the blood or interstitial fluid. glandular,adj.

Exocrine glands: structural classification

gland

(gland) [TA]

An organized aggregation of cells functioning as a secretory or excretory organ. Synonym(s): glandula (1) .

[L. glans, acorn]

gland

(gland) [L. glans, acorn]

1. An epithelial tissue that is specialized for the manufacture and export of particular molecules. Glands can be unicellular or multicellular. The multicellular glands are classified according to their architectures, e.g., multicellular glands are categorized as ducted or ductless. The cells of ductless glands secrete specific molecules into the adjacent interstitial space (paracrine glands) or into the blood stream (endocrine glands), while the cells of ducted glands (exocrine glands) secrete into a cylindrical sac (tubular glands) or into a flask-shaped sac (alveolar glands). The ducted glands are further divided into those in which there is only a single sac (simple tubular glands or simple alveolar glands) and those in which the sacs are connected by branching ducts (branched or compound glands). Glands can also be classified according to the secretory mechanisms of their cells. The most common secretory mechanism is merocrine, in which secretion-filled intracellular vesicles release their contents by fusing with the cell membrane. Other secretory mechanisms include holocrine (in which the gland cell membrane disintegrates to release its secretion), apocrine (in which the ends of the gland cells pinch off, carrying the secretion), and direct active transport of particular molecules across the gland cell membrane. Gland cells and their intertwined vascular beds can be controlled by autonomic innervation and by hormones from other glands.

2. An obsolete term for “lymph node.”

accessory gland

1. An additional (usually smaller) gland that secretes the same substances as a primary gland.

2. A gland secreting substances that enhance the function of another gland or organ; e.g., in the male reproductive tract, the prostate, which secretes fluids that improve the viability of sperm, is an accessory gland to the testis.

acinar gland

acinotubular gland

acinous gland

adrenal gland

Either of two triangular glands covering the superior surface of each kidney. Synonym: suprarenal gland See: illustration

Embryology

Each adrenal gland is a two-part organ composed of an outer cortex and an inner medulla. The cortex arises in the embryo from a region of the mesoderm that also gives rise to the gonads. The medulla arises from ectoderm, which also gives rise to the sympathetic nervous system.

Anatomy

The entire gland is enclosed in a tough connective tissue capsule from which trabeculae extend into the cortex. The cortex consists of cells arranged into three zones: the outer zona glomerulosa, the middle zona fasciculata, and the inner zona reticularis. The cells are arranged in cords. The medulla consists of chromaffin cells arranged in groups or in anastomosing cords. The two adrenal glands are retroperitoneal, each embedded in perirenal fat above its respective kidney. In an adult, the average weight of an adrenal gland is 5 g (range: 4 to 14 g).

Physiology

The adrenal medulla synthesizes and stores three catecholamines: dopamine, norepinephrine, and epinephrine. The chief effects of dopamine are the dilation of systemic arteries, increased cardiac output, and increased flow of blood to the kidneys. The primary action of norepinephrine is constriction of the arterioles and venules, resulting in increased resistance to blood flow, elevated blood pressure, and slowing of the heart. Epinephrine constricts vessels in the skin and viscera, dilates vessels in skeletal muscle, increases heart rate, dilates the bronchi by relaxing bronchial smooth muscle, increases the conversion of glycogen to glucose in the liver to increase the blood glucose level, and diminishes activity of the gastrointestinal system. The three catecholamines are also produced in other parts of the body.

The adrenal medulla is controlled by the sympathetic nervous system and functions in conjunction with it. It is intimately related to adjustments of the body in response to stress and emotional changes. Anticipatory states tend to bring about the release of norepinephrine. More intense emotional reactions, esp. those in response to extreme stress, tend to increase the secretion of both norepinephrine and epinephrine; epinephrine is important in mobilizing the physiological changes that occur in the “fight or flight” response to emergency situations.

The cortex synthesizes three groups of steroid hormones from cholesterol. These are 1) glucocorticoids (cortisol, corticosterone), which regulate the metabolism of organic nutrients and have an anti-inflammatory effect; 2) mineralocorticoids (aldosterone, dehydroepiandrosterone), which affect metabolism of the electrolytes sodium and potassium; and 3) androgens and estrogens (estradiol), which contribute to body changes at puberty. See: aldosterone; cortisol; steroid

albuminous gland

Any of the glands secreting a fluid containing albumin. See: serous gland

alveolar gland

A multicellular gland in which the cells secrete specific molecules into an oval or flask-shaped sac.

Synonym: acinar gland; acinous gland

anal gland

Any of the glands in the region of the anus. Synonym: circumanal gland

apocrine gland

Any of the glands, e.g., the mammary glands, whose cells lose some of their cytoplasmic contents in the formation of secretion.

apocrine sweat gland

Any of the sweat glands in the axillae and pubic region that open into hair follicles rather than directly onto the surface of the skin as do eccrine sweat glands. They appear after puberty and are more developed in women than in men. The characteristic odor of perspiration is produced by the action of bacteria on the material secreted by the apocrine sweat glands.

duodenal gland

Ebner glands

eccrine gland

eccrine sweat gland

Any of the skin glands that regulate body heat by secreting sweat. The number of glands ranges from 2 million to 5 million. There are over 400 per square centimeter on the palms and about 80 per square centimeter on the thighs.

endocrine gland

One of two broad categories of glands; exocrine glands are the complementary category. Endocrine glands, e.g., the thyroid gland, are ductless glands that secrete macromolecules, called hormones, directly into the bloodstream, and such glands are richly supplied by blood capillaries. The endocrine glands include the adrenals, the parathyroids, the pineal, the pituitary, and the thyroid. Major clusters of endocrine tissue are also found in the gastrointestinal tract, the hypothalamus, the ovaries, the pancreas, the testes, and the placenta. In addition, chromaffin and other neuroendocrine cells are found individually and in small clusters throughout the body. See: illustration; table

The hormones produced by endocrine cells regulate the body's salt, water, mineral, and glucose levels; they adjust the body's metabolic balances, growth rates, and reproductive cycles; and they maintain the body's stress responses. Like exocrine and paracrine cells, endocrine cells are stimulated and inhibited by autonomic axons; the activities of endocrine cells are also modulated by circulating hormones, especially pituitary hormones. Both the neural and the hormonal signals to the endocrine system are ultimately regulated by the hypothalamus of the brain, which is the integration center for the body's visceral homeostasis. See: hormone

Endocrine health disorders usually result from the production of either too much or too little of a hormone.

esophageal gland

Any of the small scattered mucous-secreting exocrine glands in the submucosa of the esophagus.

exocrine gland

One of two broad categories of glands; endocrine glands are the complementary category. Exocrine glands, e.g., the salivary glands, secrete specific molecules either onto the outer surface of the body or into a duct that empties onto surfaces that connect to the outer surface of the body. Most exocrine glands are multicellular: goblet cells are examples of unicellular exocrine glands.

Fraenkel gland

Any of the tiny glands located below the margin of the vocal cords.

fundic gland

A gastric gland in the fundus of the stomach.

gastric gland

Any of the mixed exocrine glands that form the epithelial pockets (pits) in the lining of the stomach; the glands are named for their location, e.g., cardiac glands, fundic glands, pyloric glands. Typically, the neck of the gland secretes mucus, the body of the gland secretes hydrochloric acid, and the base of the gland secretes enzymes and hormones. Synonym: peptic gland; stomach gland

interstitial gland

intestinal gland

jugular gland

glands of Krause

labial gland

Any of the alveolar glands of the mucosa of the lips.

lacrimal gland

The gland that secretes tears. It is a tubuloalveolar gland located in the orbit, superior and lateral to the eyeball, and consists of a large superior portion (pars orbitalis) and a smaller inferior portion (pars palpebralis).

lingual gland

Littré gland

Luschka gland

lymph gland

A rarely used term for “lymph node.”

major salivary gland

Any of the six large salivary glands; the two parotids, the two sublinguals, and the two submandibulars.

mammary gland

A compound alveolar gland that secretes milk. In women, these glands are made up of lobes and lobules bound together by areolar tissue. Each of the 15 to 20 main ducts, known as lactiferous ducts, discharges through a separate orifice on the surface of the nipple. The dilatations of the ducts form reservoirs for the milk during lactation. Synonym: lactiferous gland

meibomian gland

Long thin sebaceous glands aligned in parallel in a single row in the tarsal plates of the eyelids. They open along the inner free margin of the eyelid, and their lipid-rich secretion mixes with aqueous secretions of lacrimal glands to form the tear film that coats the surface of the eye. Synonym: tarsal gland

Synonym: tarsal gland

merocrine gland

A gland in which the cells remain intact during the elaboration and discharge of their secretion.

minor salivary gland

Any of the hundreds of 1 to 2 mm diameter mucous-secreting salivary glands distributed throughout the oral submucosa. These small glands are named by their locations, e.g., buccal salivary glands, lingual glands, although some glands are also known by the name of their original describers, and von Ebner glands, which are lingual salivary glands found in the circumvallate papillae of the tongue.

mixed gland

1. A gland that secretes in two different fashions, e.g., endocrine and exocrine, such as the pancreas.

2. A gland that contains two different secretory cell types, e.g., mucous and serous cells, such as in the salivary glands.

glandsof Moll

Small secretory and apocrine glands adjacent to follicles of eyelashes. Their secretions are thought to be antibacterial.

Montgomery gland

Morgagni gland

muciparous gland

nabothian gland

odoriferous gland

Any of the glands exuding odoriferous materials, as those around the prepuce or anus.

olfactory gland

Any of the glands in the olfactory mucous membranes.

oxyntic gland

Any of the gastric glands found in the fundus and body of the gastric mucosa.

palatine gland

Any of the mucous glands in the tissue of the palate.

palpebral gland

Tarsal gland.

parathyroid gland

Any of four small endocrine glands about 6 mm long by 3 to 4 mm broad on the back of and at the lower edge of the thyroid gland or embedded within it. These glands secrete parathormone.

Abnormalities

An excess of parathormone results in hyperparathyroidism; a deficiency, in hypoparathyroidism, with neuromuscular hyperexcitability manifested by carpopedal spasm, wheezing, muscle cramps, urinary frequency, mood changes, and lassitude. Blood calcium falls and blood phosphorus rises. Other symptoms include blurring of vision caused by cataracts, poorly formed teeth if onset was in childhood, maldevelopment of hair and nails, and dry and scaly skin. Hyperparathyroidism or hypersecretion results in a rise in blood calcium and fall in blood phosphorus. Calcium is removed from bones, resulting in increased fragility. Muscular weakness, reduced muscular tone, and general neuromuscular hypoexcitability occur. Osteitis fibrosa cystica is associated with hyperplasia and resulting hypersecretion of the parathyroids.

paraurethral gland

parotid gland

The largest of the salivary glands, located below the ear and inside the ramus of the mandible. It is a compound tubuloalveolar serous gland. Its secreting tubules and acini are long and branched, and it is enclosed in a sheath, the parotid fascia. Saliva lubricates food and makes it easier to taste, chew, and swallow. See: mumps

peptic gland

Peyer glands

An obsolete term for Peyer patch.

pineal gland

An endocrine gland in the brain, shaped like a pine cone and located in a pocket near the splenium of the corpus callosum. It is the site of melatonin synthesis, which is inhibited by light striking the retina. Synonym: pineal body; See: melatonin

PITUITARY GLAND: Hormones secreted by the anterior and posterior pituitary gland, along with target organs

pituitary gland

A small, gray, rounded gland that develops from ingrown oral epithelium (Rathke pouch) and is attached to the lower surface of the hypothalamus by the infundibular stalk. The Rathke pouch portion forms the anterior lobe and an intermediate area; the neural tissue of the infundibular stalk forms the posterior lobe. The pituitary gland averages 1.3 × 1.0 ×0.5 cm in size and weighs 0.55 to 0.6 g. Synonym: hypophysis; hypophysis cerebri See: illustration

Function

The pituitary is an endocrine gland secreting a number of hormones that regulate many bodily processes including growth, reproduction, and other metabolic activities. It is often referred to as the “master gland of the body.”

Hormones are secreted in the following lobes: Intermediate lobe: In cold-blooded animals, intermedin is secreted, influencing the activity of pigment cells (chromatophores) of fishes, amphibians, and reptiles. In warm-blooded animals, no effects are known.

Anterior lobe: Secretions here are the somatotropic, or growth hormone (STH or GH), which regulates cell division and protein synthesis for growth; adrenocorticotropic hormone (ACTH), which regulates functional activity of the adrenal cortex; thyrotropic hormone (TTH or TSH), which regulates functional activity of the thyroid gland; and prolactin, also called lactogenic hormone, which induces secretion of milk in the adult female. The gonadotropic hormones are as follows: in women, follicle-stimulating hormone (FSH) stimulates development of ovarian follicles and their secretion of estrogen; in men, it stimulates spermatogenesis in the testes. In women, luteinizing hormone (LH) stimulates ovulation and formation of the corpus luteum and its secretion of estrogen and progesterone. In men, LH also called interstitial cell-stimulation hormone (ICSH), stimulates testosterone secretion.

Posterior lobe: Hormones are secreted by the neurosecretory cells of the hypothalamus and pass through fibers of the supraopticohypophyseal tracts in the infundibular stalk to the neurohypophysis, where they are stored. Secretions here are oxytocin, which acts specifically on smooth muscle of the uterus, increasing tone and contractility, and antidiuretic hormone (ADH), which increases reabsorption of water by the kidney tubules. In large amounts, ADH also causes vasoconstriction, and is also called vasopressin.

preputial gland

prostate gland

The gland in the male that surrounds the neck of the bladder and the urethra. It is partly glandular, with ducts opening into the prostatic portion of the urethra, and partly muscular. It secretes a thin, opalescent, slightly alkaline fluid that forms part of the semen. The prostate consists of a median lobe and two lateral lobes measuring about 2 × 4 × 3 cm and weighing about 20 g; it is enclosed in a fibrous capsule containing smooth muscle fiber in its inner layer. The nerve supply is from the inferior hypogastric plexus.

pyloric gland

A gastric gland in the pyloric region of the stomach.

racemose gland

Acinar gland.

Rivinus gland

salivary gland

Any of the glands near the oral cavity that secrete saliva. The major glands are paired and include the parotid, the sublingual, and the submandibular. There are numerous minor salivary glands in the oral cavity, named according to their locations: lingual, sublingual, palatal, buccal, labial, and glossopharyngeal. See: illustration

Salivary secretion is under nervous control, reflexly initiated by mechanical, chemical, or radiant stimuli acting on taste buds in the mouth, olfactory receptors, or the eyes. Secretion may also be due to conditioned reflexes as when one thinks about food or hears a dinner bell. The nerve supply of the salivary glands is from the facial and glossopharyngeal nerves, which increase secretion, and from the sympathetic nerves, which decrease secretion. The blood supply is from branches of the external carotid artery.

sebaceous gland

An oil-secreting gland of the skin. The glands are simple or branched alveolar glands, most of which open into hair follicles. They are holocrine glands whose secretion arises from the disintegration of cells filling the alveoli. Some aberrant glands are found in the cheeks or lips of the oral cavity, well separated from hair follicles.

sentinel gland

A term formerly used to indicate a sentinel lymph node, i.e., a lymph node that first alerts a clinician to serious pathology (such as a spreading cancer).

seromucous gland

A mixed serous and mucus gland.

serous gland

An exocrine gland with a relatively watery secretion, isotonic with blood plasma, and containing enzymes, glycoproteins, lysozymes, and bactericides. Serous glands are most common in the gastrointestinal tract, notably in the salivary glands.

sex gland

An ovary or testis.

simple gland

A gland shaped like a single unbranched sac. When the sac is cylindrical, the gland is called simple tubular; when the sac is flask-shaped, the gland is called simple alveolar.

Skene gland

stomach gland

sublingual gland

The smallest of the major salivary glands, located in the tissue in the floor of the mouth between the tongue and mandible on each side. It is a mixed seromucous gland. Its main duct opens into or near the submandibular duct, but several smaller ducts may open to the oral cavity independently along the sublingual fold. Numerous minor sublingual glands are scattered throughout the mucosa under the tongue, each with its own duct to the oral surface.

submandibular gland

A mixed tubuloalveolar salivary gland about the size of a walnut that lies below the posterior floor of the mouth, medial to the body of the mandible. Its main duct (Wharton duct) opens at the side of the frenulum linguae.

sudoriferous gland

suprarenal gland

sweat gland

Any of the simple, coiled, tubular glands found on all body surfaces except the margin of the lips, glans penis, and inner surface of the prepuce. The coiled secreting portion lies in the corium or subcutaneous portion of skin; the secretory duct follows a straight or oblique course through the dermis but becomes spiral in passing through the epidermis to its opening, a sweat pore. Most sweat glands are merocrine; those of the axilla, areola, mammary gland, labia majora, and circumanal region are apocrine. Sweat glands are most numerous on the palms of the hands and soles of the feet.

target gland

tarsal gland

thymus gland

thyroid gland

A large endocrine gland located in the center of the base of the neck. The gland is composed of two lobes, one on each side of the trachea, and an isthmus of tissue connecting the lower two thirds of each lobe. The isthmus is usually located at the level of the second to third tracheal rings. The whole gland is surrounded by a thin fibrous capsule attached in back to the cricoid cartilage and the first few tracheal rings. The lobes of the thyroid lie under the sternothyroid and sternohyoid muscles. The thyroid is filled with capillary networks (supplied by the superior and inferior thyroid arteries) that surround the many spherical units (follicles) packed inside the gland. Thyroid follicles consist of a ring of follicular cells surrounding a space filled with a clear colloid (a mixture of thyroglobulin proteins and iodine), from which the thyroid hormones (thyroxine and related molecules) are synthesized. These hormones regulate the rate of cellular metabolism throughout the body. All the steps in synthesizing and releasing thyroid hormones are stimulated by thyroid-stimulating hormone (TSH) secreted by the pituitary gland. Another class of thyroid cells, the parafollicular or C cells, is found outside the follicles; C cells secrete calcitonin, a calcium-lowering hormone.

See: illustration

tracheal gland

Any of the acinar glands of the tracheal mucosa.

tubular gland

A multicellular gland in which the cells secrete specific molecules into a cylindrical sac.

Tyson gland

unicellular gland

A lone secretory epithelial cell, often found in the midst of nonsecretory cells. A common example is the goblet (chalice, calceiform) cell, a unicellular mucous-secreting gland found in the columnar epithelium of the intestinal tract.

von Ebner gland

vulvovaginal gland

Waldeyer gland

Weber gland

glands of Zeis

Small sebaceous glands surrounding the follicles of eyelashes. Their lipid-rich secretions coat the shafts of lashes.

gland

A cell or organized collection of cells capable of abstracting substances from the blood, synthesizing new substances, and secreting or excreting them into the blood (endocrine glands), into other bodily structures or on to surfaces, including the skin (exocrine glands). The simplest glands are single mucus-secreting goblet cells. Glands also produce digestive enzymes, hormones, tears, sweat, milk and sebum. LYMPH NODES are often miscalled ‘glands’.

gland

an organ producing substances which are then secreted to the outside of the gland, sometimes by means of a duct, as in the exocrine glands, for example, the salivary mammary, lachrymal glands, but also in the case of ENDOCRINE GLANDS directly into the blood or lymphatic systems. Occasionally individual cells act as glands, for example, gland cells of Hydra producing digestive enzymes.

Gland

A collection of cells whose function is to release certain chemicals, or hormones, which are important to the functioning of other, sometimes distantly located, organs or body systems.

gland

an organ or structure whose cells produce a secretion: exocrine, delivered via ducts to the skin surface or an internal surface, e.g. in the gut, or endocrine, passed into the blood stream. See alsodigestion, hormones, sweating.

gland,

n an organ with specialized cells that secretes or excretes materials into the body. Classified into exocrine glands that secrete via ducts and endocrine glands that secrete directly into the bloodstream.

gland

An aggregation of cells which secretes or excretes a substance. There are two main groups of glands: (1) The endocrine glands which have no duct and whose secretion (a hormone) is absorbed directly into the blood. Examples: adrenal gland, pineal gland, pituitary gland, thyroid gland. (2) The exocrine glands whose secretion reaches the surface by means of ducts. There are three main types of secretion by exocrine glands: the serous glands which secrete a watery substance rich in proteins (e.g. lacrimal gland, sweat glands), the mucous glands which secrete mucus, a viscous product (e.g. goblet cells), and the sebaceous glands which secrete a lipid substance (e.g. meibomian glands).accessory lacrimal gland's They are the glands of Krause and Wolfring. These glands are histologically identical to the main lacrimal gland, but are located within the eyelids. These glands are responsible for basal (not reflex) tear secretion and appear to be under sympathetic neural control.gland's of CiaccioSeeglands of Wolfring.ciliary sebaceous gland'sSeeglands of Zeis.ciliary sweat gland'sSeeglands of Moll.conjunctival gland Any gland that secretes a substance into the conjunctiva, such as the lacrimal, meibomian, Krause and Wolfring glands or a goblet cell.gland's of Henle These are not really glands. They are folds in the mucous membrane of the palpebral conjunctiva, situated between the tarsal plates and the fornices, in which there are goblet cells (Fig. G2). Syn. crypts of Henle (strictly speaking this term refers only to the pit-like depressions).gland's of Krause Accessory lacrimal glands of the conjunctiva having the same structure as the main lacrimal gland. They are located in the subconjunctival connective tissue of the fornix, especially the superior fornix (Fig. G2).lacrimal gland A compound gland situated above and to the outer side of the globe of the eye. It consists of two portions: (1) a large orbital or superior portion; and (2) a small palpebral or inferior portion. It secretes the middle aqueous layer of the tears through about a dozen fine ducts into the conjunctival sac at the upper fornix although one or two may also open into the outer part of the lower fornix (Fig. G2). Seedacryoadenitis; dacryops; fossa for the lacrimal gland; zygomatic nerve; tear duct.gland's of Manz Tiny glands located near the limbus. They secrete mucin. The existence of these glands in man is not established.meibomian gland's Sebaceous glands located in the tarsal plates of the eyelids whose ducts empty into the eyelid margin. They are arranged parallel with each other, perpendicular to the lid margin, about 25 for the upper lid and 20 for the lower. They secrete sebum. This sebaceous material provides the outermost oily (or lipid) layer of the precorneal tear film. It prevents the lacrimal fluid from overflowing onto the outer surface of the eyelid. It also makes for an airtight closure of the lids and prevents the tears from macerating the skin. The meibomian glands can be seen showing through the conjunctiva of fair-skinned people as yellow streaks (Fig. G2). Meibomian gland dysfunction (MGD) may be induced by blepharitis, chalazion, contact lens wear (particularly soft lenses) and ageing. The most common sign is a cloudy or absent secretion upon expression with symptoms of a mild dry eye. Hot compresses and lid massage will cure more than half of the patients; oral tetracycline will help in many of the others. Syn. palpebral follicles; tarsal glands. Seeposterior blepharitis; chalazion; precorneal film; internal hordeolum; keratoconjunctivitis sicca; meibomianitis; tarsus; Tearscope plus.gland's of Moll Sweat glands of the eyelids. They are situated in the region of the eyelashes (Fig. G2). Syn. ciliary sweat glands.tarsal gland's Seemeibomian glands.gland's of Wolfring Accessory lacrimal glands of the upper eyelid situated in the region of the upper border of the tarsus (Fig. G2). Syn. glands of Ciaccio.gland's of Zeis Sebaceous glands of the eyelids which are attached directly to the follicles of the eyelashes. Their secretion contributes to the oily layer of the precorneal film (Fig. G2). Syn. ciliary sebaceous glands. Seemarginal blepharitis; hordeolum.

Fig. G2 Section diagram of the upper eyelid showing the various glands

gland

(gland) [TA]

Organized aggregation of cells functioning as a secretory or excretory organ.

[L. glans, acorn]

gland(s),

n/n.pl an organ producing a specific product or secretion.

gland, parotid salivary,

n the largest of the major salivary glands; its anterior position is situated between the ramus of the mandible, its posterior portion between the mastoid process and sternocleidomastoid muscle, and inferior to the zygomatic arch; irregularly wedge shaped, with the lateral surface flattened and the medial aspect more or less pointed toward the pharyngeal wall. Its secretion, which is serous, travels the parotid duct (Stenson's duct) to empty into the oral cavity at the ductal opening at the parotid papillae on the buccal mucosa opposite the maxillary molar teeth.

gland, pituitary,

n (hypophysis), an endocrine gland located at the base of the brain in the sella turcica. The pituitary gland is composed of two parts: the pars nervosa, which is an extension of the anterior part of the hypothalamus, and the pars intermedia, which is an epithelial evagination of secretory tissue from the stomodeum of the embryo. By its structural and functional relationships with the nervous system and the endocrine glands, it acts as a mediator of both the nervous system and the endocrine system.

gland, sublingual salivary,

n the smallest of the major salivary glands. It lies inferior to the floor of the oral cavity bilateral to the lingual frenum and is in contact with the sublingual depression on the inner side of the mandible. Its numerous ducts open directly into the oral cavity bilateral to the lingual frenum and join to form the sublingual duct (duct of Bartholin's), which enters into the submandibular duct (Wharton's duct). Its secretion is mucous in nature.

gland, submandibular salivary,

n a major salivary gland that has an irregular form and is situated in the submandibular space, bordered anteriorly by the anterior belly of the digastric muscle and posteriorly by the stylomandibular ligament. Its mucoserous section is carried by the submandibular duct (Wharton's duct), whose openings lie at a small papilla (submandibular caruncle) bilateral to the lingual frenum.

n.pl the ducted (exocrine) glands that produce lacrimal fluid, commonly called tears. See also lacrimal apparatus.

glands, minor salivary,

n.pl the glands located at the posterior aspect of the dorsum of the tongue posterior to the circumvallate papillae (von Edner's) and along the lateral surface of the tongue; also located in the palate, floor of mouth, labial mucosa, and buccal mucosa. The secretion is mucous, and they do not have named ducts. Older term: accessory salivary glands. See also salivary glands, von Edner's.

glands, salivary,

n.pl the glands in the oral cavity that secrete saliva. Three major salivary glands contribute their secretions to form the whole saliva; the minor mucous glands found within oral mucosa contribute a lesser amount. The major salivary glands are the parotid, submandibular, and sublingual.

gland

an aggregation of cells specialized to secrete or excrete materials not related to their ordinary metabolic needs. Glands are divided into two main groups, endocrine and exocrine.

Specific glands will be found under their individual names.

accessory genital g's

glands other than the gonads, intimately associated with the reproductive organs, especially of the male, in which they include vesicular glands (seminal vesicles), ampullary glands, prostate, bulbourethral glands, coagulating glands. Called also accessory sex glands.

accessory sex gland

see accessory genital glands (above).

acinous gland

one made up of one or more oval or spherical sacs (acini).

alveolar gland

one whose secretory units consist of saclike dilatations with a distinct lumen.

alveolar-tubular gland

gland composed of a mixture of alveolar and tubular structures.

ampullary gland

fusiform enlargement of the deferent duct, as it passes across the bladder wall, due to proliferation of glandular tissue in the regionally folded mucosa.

anal g's

small glands in the anal columnar mucosal cells plus larger and more numerous circumanal glands in the surrounding skin.

apocrine gland

one whose discharged secretion contains part of the secreting cells.

avian stomach g's

mucosal and submucosal glands in the stomach of birds; the submucosal glands are thought to secrete both acidic and enzymic substances.

bronchial g's

glands which contain a mixture of serous and mucus-secreting cells found in the bronchial mucosa.

buccal g's

buccal salivary glands lying in the submucosal tissues of the cheek and sometimes the orbit and whose ducts secrete directly into the buccal cavity.

cardiac gland

one of the three (the other two are the pyloric and proper gastric or fundic) types of gland in the stomach wall and capable of secretion into the gastric juices; this gland secretes only mucus.

carpal g's

cutaneous, 'marking' glands found on the medial aspect of the carpus in the pig; although present in both sexes are thought to be used to mark mated females.

circumoral g's

large glands in the lips of cats; used to mark territory either directly by the familiar fawning head rub, or indirectly by rubbing the secretion of the gland onto the fur during grooming.

ceruminous g's

cerumin-secreting glands in the skin of the external auditory canal.

compound gland

one made up of a number of smaller units whose excretory ducts combine to form ducts of progressively higher order.

deep (lacrimal) gland, gland of the third eyelid

an additional lacrimal gland found in the skin of the cartilaginous support of the third eyelid.

ductless g's

endocrine glands.

eccrine gland

a gland that secretes its product without loss of cytoplasm, such as the sweat glands on dog footpads or human skin.

endocrine g's

or ductless glands, discharge their secretions (hormones) directly into the blood; they include the adrenal, pituitary, thyroid and parathyroid glands, the islets of Langerhans in the pancreas, the gonads and the pineal body.

exocrine g's

discharge through ducts opening on an external or internal surface of the body; include the salivary, sebaceous and sweat glands, the liver, the gastric glands, the pancreas, the intestinal, mammary and lacrimal glands, and the prostate.

fundic g's, fundus g's

numerous, tubular glands in the mucosa of the stomach that contain the cells which produce acid and pepsin. According to the species, they are usually found in the body and occasionally in the fundus.

gustatory gland

branched, tubuloalveolar serous glands which open into large lingual papillae.

hematopoietic gland

glandlike body, e.g. the spleen, that takes a part in blood formation.

hemolymph gland

small node resembling lymph node but red or brown in color and containing blood sinuses instead of or alongside lymph spaces. Common in ruminants and some rodents and typically located along the large arteries.

one whose discharged secretion contains the entire secreting cells as in sebaceous glands.

horn gland

a scent gland found caudomedial to the horn base in goats of both sexes; increase in size and activity in breeding season. Produce the pungent secretion so characteristic of goats, described best as the distilled essence of reek.

infraorbital g's

special sebaceous glands which line the infraorbital sinus (pouch) in sheep.

inguinal g's

the collection of special tubular and sebaceous glands which line the inguinal pouch (sinus) in sheep.

interdigital g's

special sebaceous and tubular glands in the interdigital sinus (pouch) in sheep.

intestinal g's

microscopic tubular glands which lie in the mucosa of the gut and secrete intestinal juice into the lumen of the small intestine.

labial g's

minor salivary glands; mucous in small ruminants, serous in others.

lateral nasal g's

a local glandular thickening of the mucosa lining the maxillary sinus of dogs and some other species; this tissue is largely responsible for the continually wet nose of the dog.

mucous glands containing lymphoid tissue located in the proctodeum of male and female birds.

proper gastric gland

the main digestive glands of the stomach; found in different parts of the stomach in different species but usually in the body of the stomach; secrete pepsin and hydrochloric acid; open into microscopic pits and clefts.

scent gland

secrete pheromones which play such a large part in olfactory communication between animals. Located in a variety of places, e.g. in the elephant they are behind the eyes, in the musk deer they are in the belly wall.

the caudal portion of the uterus in the female bird in which the egg is held while the shell is secreted.

simple gland

one with a nonbranching duct.

sine ductibus gland

ductless gland.

solitary g's

solitary follicles.

sperm host gland

in the vagina of birds; store and nourish visiting spermatozoa which are released when oviposition occurs.

splenolymph g's

hemolymph glands having more of the splenic type of tissue.

sublingual salivary gland

a major salivary gland; predominantly mucous cells in ruminants, swine, rodents; mixed serous and mucoid cells in small carnivores and horses.

submental g's

a group of sebaceous glands in the intermandibular space in cats.

submucosal intestinal g's

simple, branched, tubuloacinar glands; mucous in ruminants and dogs, mixed serous and mucous in cats and serous in horses and dogs; in carnivores and small ruminants confined to the proximal or middle parts of the duodenum, extend to jejunum in large ruminants, horses, pigs.

small tubuloalveolar glands in subconjunctival tissue above the upper border of the tarsal plate; open onto conjunctiva.

g's of Zeis, Zeis g's

prominent sebaceous sweat glands on the eyelid margins, associated with hair follicles of cilia. See also external hordeolum.

Zuckerkandl gland

two large bodies included with the paraganglia along the abdominal aorta.

zygomatic salivary gland

a unique salivary gland in small carnivores; contains mainly mucous cells with a few serous cells; a modified dorsal buccal gland.

supracaudal organ, gland

a collection of large sebaceous glands in the skin of the dorsum of the tail in cats. Excessive sebaceous secretion with inflammation gives rise to the condition known as stud tail.

Patient discussion about gland

Q. Anyone know if there is a connection between Fibromyalgia and your Thyroid gland? I have Fibromyalgia and I read that if your diagnosed with this you can have Thyroid problems also. If anyone knows out there please inform me. Many thanks.

A. Below is an interesting article on the subject. A significant percentage of the estimated 20 million people with hypothyroidism end up also being diagnosed with fibromyalgia. Some experts believe that like most cases of hypothyroidism, fibromyalgia is also autoimmune in nature. Others believe that fibromyalgia may be one manifestation of an under active metabolism – hypometabolism – and is therefore one variation on thyroid dysfunction.http://thyroid.about.com/cs/fibromyalgiacfs/a/fibrothyroid.htm

Q. my friend ate a bar of chocolate and now her left neck gland is swollen any ideas why? no other symptoms

A. it can be an infection -just like brandon said- or although this is rare, it can also be an allergic reaction. if it is an infection, you can usually find such other infection symptoms like : fever, pain in that swollen area, increased white blood cells (in blood work test), etc.

if it is an allergy, usually it will fade away itself in couple of days, or you can just try to consume anti-allergic drugs, such as : loratadine and maybe combined with dexamethasone.

This study aimed to evaluate the effects caused by episodic and intense intoxication of EtOH in a 3-day/week binge pattern on the parotid and submandibular salivary glands of female rats, during adolescence to young adulthood phase.

INTRODUCTION: The term "ranula" is used to describe a diffuse swelling in the floor of the mouth caused by either a mucous extravasation or, less commonly, a mucous retention cyst derived from the major sublingual or submandibular salivary glands.

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